Notes, abstracts, papers, exams and problems of Biology

Arthropod Characteristics

Arthropods exhibit bilateral symmetry and a ventral nervous system. Their heart is positioned dorsally, and they have an open circulatory system. They possess an external chitinous exoskeleton, which they shed and replace with a new one during growth, a process called molting. The sensory organs of arthropods are highly developed, primarily located in the head and legs.

Chordate Features

• The alimentary canal includes glands that aid digestion, such as salivary glands, the pancreas, and the liver.
• The cerebrospinal nervous system consists of a thick dorsal nerve cord, forming the brain and spinal cord, with nerves branching out.
• Most chordates have separate sexes. Development typically occurs in eggs, although mammals and

Levels of organization refer to the different degrees of complexity in organized matter.

• Subatomic level: Particles that make up atoms (protons, neutrons, electrons).
• Atomic level: Formed by atoms; the smallest constituents of matter that retain their properties.
• Molecular level: Molecules resulting from the binding of different atoms. There are two types:
  • Inorganic: Found in non-living or dead material (water and mineral salts).
  • Organic: Found only in living matter, usually polymers, chains formed by the union of a similar type of monomer molecules.
• Cellular level: The first level with life.
• Tissue level: Groups of cells with the same function and similar structure.
• Organ level: Different tissues are grouped for a particular function.
• System level:

Mitochondria: Structure and Function

In mitochondria is where cellular respiration occurs (specifically the Krebs cycle, beta-oxidation, electron transport, and oxidative phosphorylation), whose ultimate objective is to obtain energy in the form of ATP. Mitochondria also generate precursors of the major anabolic routes.

The mitochondria are structured as follows: a double membrane formed by an external and an internal membrane, which delimits two different compartments: the intermembrane space and the mitochondrial matrix.

The Outer Mitochondrial Membrane

The outer mitochondrial membrane is in continuous contact with the cytosol. It contains numerous proteins that regulate trade in chemicals with it, including channel proteins (porins) that form... Continue reading "Mitochondrial Structure and Function in Cellular Respiration" »

Forest Ecosystems: A Comprehensive Look

Forest: A natural ground dominated by trees. Vegetation: Various species of plants with 3 strata: arboreal, shrubby, and herbaceous. Conditions: Light, heat. Virosta: Composition of residue that accumulates sun.

Plant Types

• Bryophytes (moss, liverwort)
• Pteridophytes (fern, horsetail)
• Spermatophytes (seed plants)

Gymnosperms (not enclosed seeds). Angiosperms (enclosed seeds). Vegetation Zones: Forest (arboreal), thicket (tall shrub), springs (low shrub), meadow (herbaceous).

Revolt: Perennial, deciduous. Mineral salts (active absorption via PX transport - against gradient, sometimes with gradient). Concentration: Hypotonic (-), isotonic (=), hypertonic (+).

Osmosis and Photosynthesis

Osmosis: Process of water absorption... Continue reading "Understanding Forest Ecosystems: Flora, Soil, and Life Cycles" »

Interaction

Interaction is the set of processes through which a living being obtains information from the environment, takes decisions, controls its actions, and coordinates the functioning of the body itself.

Obtaining Information

There are various mechanisms responsible for obtaining information from the exterior and the interior of the body. These mechanisms are called receptors.

Analysis of the Information and Elaboration of a Response

This process is carried out by the nervous system and the endocrine system. The elaborated response is an order that is transmitted to the organs via different procedures.

Execution of a Response

The effectors, which are the organs responsible for carrying out a response, are as varied as the possible responses... Continue reading "Interaction: Obtaining, Analyzing, and Executing Responses in Living Beings" »

Types of Illness

• Physical Diseases: Caused by injury, infection, or degenerative processes in the body. They are classified into infectious and non-infectious diseases.
• Mental Illness: Provoked by a malfunction of the brain.
• Social Ills: Caused by the existence of a social environment with serious violent, economic, or educational deprivation.

Health vs. Illness

• Health: A state of complete physical, mental, and social well-being.
• Illness: The state in which a person's health is disturbed.

Violence as a Social Disease

Violence is a terrible social disease that kills many people every year. It is a disease that is incubated in childhood.

Viruses

Viruses are not living creatures but protein capsules containing DNA or RNA that is injected into a cell.

Infectious

Sutton's Chromosome Theory of Inheritance

• Chromosomes occur in pairs.
• Chromosome pairs separate during meiosis.
• Each gamete carries one chromosome from each pair.
• Pairs of chromosomes separate independently of other pairs.
• Fertilization restores the paired condition of chromosomes in the zygote.

Mendel's Laws of Inheritance

• Factors (genes) occur in pairs.
• Factors segregate to form gametes.
• Each gamete carries a single factor.
• Pairs of factors separate independently of other pairs.
• Fertilization restores the paired condition of factors in the zygote.

Chromosomal Abnormalities

Trisomies

• Down Syndrome (Trisomy 21): Congenital mental disability, distinct facial profile, increased risk of illness, and heart defects.
• Patau Syndrome (Trisomy 13): Nerve abnormalities,

Key Definitions in Health and Disease

Agent: An animate or inanimate entity whose presence or absence can disrupt host health.

Host: Any organism capable of harboring an agent.

Environment: The complex of factors influencing a system, determining its course and way of life.

Stimulus Trigger: A factor or condition arising after a disturbance in the ecological triad's balance, initiating the disease process.

Sign: A measurable or quantifiable manifestation in an individual.

Symptom: A subjective expression of a condition reported by an individual.

Latency: A stable phase in disease evolution without subclinical manifestations, signs, or symptoms.

Causality: Conditions involving agent, host, environment, and transmissibility factors that generate a stimulus... Continue reading "Understanding Health: Agents, Hosts, and Environmental Factors" »

Invertebrate Excretory Systems (Protonephridia): These are found in animals with no coelom, such as flatworms. They consist of highly branched tubes that end in a few cells with cilia (flame cells) or flagella (solenocytes). Both cilia and flagella are located in the lumen of the tube, and their movement causes the continuous elimination of waste substances. (Metanephridia): This system occurs in coelomates (annelids, mollusks, etc.). It is made up of a coiled tube surrounded by a capillary network, with two openings: the external (nephridiopore) and internal (nephrostome), which opens into the coelomic cavity. Inside the metanephridia, reabsorption occurs for compounds that are still useful, while waste substances are expelled outside through... Continue reading "Understanding Invertebrate and Vertebrate Excretory Systems" »

Unit 10: The Basis of Heredity - Molecular Genetics

Basics of Genetics

• Gene: Each piece of DNA containing information for one character.
• Alleles: Each form a gene can have.
• Locus: The physical location a gene occupies on a chromosome.
• Loci: The place occupied by several genes.
• Diploid Organisms: Individuals who have two alleles for each gene, one from the mother and one from the father. This is represented as 2n.
• Haploid Organisms: Individuals that have only one gene for each character. This is represented by n.
• Gamete: A sexual reproductive cell, haploid (n), produced by meiosis.
• Genotype: The set of alleles of an individual for one or more characters.
• Phenotype: Each of the aspects or observable manifestations of a character.
• Phenotype = Genotype +